You can earn credits used to purchase new cars and upgrades in DiRT Rally 2.0 only in the career more and through daily and weekly challenges. Completing a race in career mode in Rallycross requires less time than in the case of a regular rally race and will reward you with the appropriate amount of cash quicker.

If you do not want to waste money earned through races on repairs and want to focus on increasing your reservoir of credits, use one of the default cars for the races - Lancia Fulvia in rally and Opel Corsa in Rallycross. You can repair both of them for free.